Most MOS semiconductor products require burn-in and testing to avoid field failures due to devices which are faulty when manufactured. Some procedures use stress by probing at elevated voltages to detect and sort faulty chips before packaging and burn-in.
High pin count contact assemblies similar to the ones used in conventional wafer probe systems are not practical due to the difficulty in maintaining good contact with all the bond pads, between 3000 and 6000, during the burn-in period. This period can range from 20 hours to 120 hours. The construction of such high pin count burn-in probes is expensive, if not impossible.
A flexible, reusable contact assembly, fabricated using plating techniques is less expensive than individual pin probes, but this type of contact cannot be used with bare aluminum bond pads due to the natural oxide on aluminum bond pads. A bumping or oxide removal step is generally required of the bond pad before this type contact assembly can be used. This application, however, is very sensitive to contact pressure and deemed impractical.